The \(e^+ e^- \rightarrow \pi ^+\pi ^-\eta ^{\prime }(\eta )\)  processes are also
studied in the Resonance Chiral Theory framework and the
extended Nambu-Jona-Lasinio model [1]}, [2]}, [3]}, [4]}, [5]}. However,
most of the comparisons of experimental data with those theory predictions are performed in
the energy region below 2.0 GeV. With more resonances being included and precise experimental measurements available, these theory models could be tested above 2 GeV in the future.
